In recent years, the phenomenon of housing vacancy rate (HVR) has attracted considerable attention, especially concerning unjustified expansions of Chinese cities. The aforementioned trend is disadvantageous in that it will ultimately lead to tremendous wastage of valuable land that could otherwise be more productively utilized. Consequently, the methods for accurately determining the HVR are of great importance. Based on nighttime light data from the Luojia 1-01 nighttime light imagery provided by Wuhan University in June 2018 and the building data obtained from the Resources and Environmental Sciences Data Center, we estimated the HVRs of 49 cities in China by determining the building areas and considering the floor height. The results revealed that (1) the lowest (15%) and highest (24.3%) HVRs occur in Shenzhen and Nanning, respectively. (2) The urban HVR correlates positively with the three production structures (0.3143) but is significantly negatively correlated with population (0.3841), GDP (0.6139), and urban average housing prices (0.5083). (3) The first-tier, new first-tier, and second-tier cities showed the lowest (16.9%), relatively concentrated (20.5%), and highest (21.3%) average vacancy rates, respectively. (4) The vacancy rate is relatively low in the eastern coastal areas, whereas high in the northeast and western inland areas. The proposed method can help urban planners by identifying vacant areas and providing building information.

Geographically, the coastal zone is a unit where the marine system and the terrestrial system intersect and have the closest relationship with human survival and development. The study of coastal-zone land use change is therefore of great significance in promoting the sustainable development of coastal areas in terms of resources and environment. However, the relationship between urban land use change and distance from the coastline is indeterminate in current research. This paper aims to assess the spatial and temporal characteristics of coastal land use change with the sea–land gradient, as well as to reveal the role of coastal ecosystems. The indices of the dynamic index, net transfer matrix, and aggregation index were measured in different coastal buffer zones quantitatively. A case study of Dalian between 2000 and 2015 indicates that Dalian’s urban construction land is distributed among the coastal zones with a high total and fast growth rate. The land use conversion direction varies significantly between different buffer zones, with [0, 2.5] km tilted mainly towards urban types and [10, Max] km tilted mainly towards rural areas. The aggregation of land use structure in Dalian fluctuated and increased year by year. As the distance from the coastline gets closer, land use is going to get more diverse.